1. Field of the Invention
The present invention relates to a magnetic recording/reproduction apparatus useful as a video tape recorder (VTR).
2. Description of the Related Art
In recent years, magnetic recording/reproduction apparatus such as VTRs tend to use an ultra thin magnetic tape as a recording medium in response to demands for digitization of data and long-time recording/reproduction.
Such an ultra thin tape is subjected to the following operation by a mechanism of a magnetic recording/reproduction apparatus. The ultra thin tape is drawn out from a tape cassette and loaded to pass around a predetermined portion of the periphery of a rotary head cylinder in this manner, the tape is kept in contact with a magnetic head disposed on the rotary head cylinder while running, so as to effect recording/reproduction of information on/from the tape. The tape is then rewound onto a reel in the cassette, and the cassette is ejected. If the tape is damaged, e.g., scratched or broken during this sequence of operations, in particular, during the loading and unloading operations, a serious quality problem arises. Therefore, great care must be taken to avoid such a problem. For example, if the cassette is attempted to be ejected while the tape is slacked, a cassette cover is closed with the tape being drawn out from the cassette, causing great damage to the tape.
In VTRs, various means are taken to ensure safe ejection of the tape cassette even when an abnormality occurs during tape running.
A conventional magnetic recording/reproduction apparatus is disclosed it Japanese Laid-Open Utility Model Publication No. 61-195552. Referring to FIGS. 40 and 41, the conventional magnetic recording/reproduction apparatus will be described.
A conventional magnetic recording/reproduction apparatus 300 includes a typical tape path where a tape 316 is drawn out from a tape cassette 310 and passes around a rotary head cylinder 318 for recording and reproduction.
The tape 316 is driven by rotating a capstan 320 with a capstan motor 323 while a pinch roller 319 is pressed against the capstan 320. The rotation of the capstan motor 323 is also transmitted to a fixed gear 332 and a swing gear 334 via gears 324 and 325 and a timing belt 326, and then transmitted selectively to a driving gear 328 of an S reel base 301 or a driving gear 329 of a T reel base 302.
The swing gear 334 is swingably attached to a shaft 339 extending from a swing plate 333, which is in turn swingably attached to a shaft of the fixed gear 332.
In the conventional magnetic recording/reproduction apparatus having the above configuration, when the tape is to be sent forward (e.g., when recorded images are to be reproduced, the tape is to be fast-forwarded, etc.), the apparatus works as follows. The capstan motor 323 is rotated forward (counterclockwise (CCW)), rotating the capstan 320 forward. This allows the tape 316 to be sent forward. At the same time, the rotation of the capstan 320 is transmitted to the fixed gear 332 via the timing belt 326, which causes the swing plate 333 to swing clockwise (CW) around a shaft 331 and thus the swing gear 334 to engage with the driving gear 329 of the T reel bass 302. The T reel base 302 then rotates clockwise, thereby allowing the tape 316 to be wound onto a winding reel inside the tape cassette 310.
In reverse, when the tape is to be sent backward (e.g. when recorded images are to be reproduced in reverse, the tape is to be rewound, etc.), the apparatus works as follows. The capstan motor 323' is rotated backward (clockwise), rotating the capstan 320 backward. This allows the tape 316 to be sent backward. At the same time, the rotation of the capstan 320 is transmitted to the fixed gear 332 via the timing belt 326, which causes the swing plate 333 to swing counterclockwise around the shaft 331 and thus the swing gear 334 to engage with the driving gear 328 of the S reel base 301. The S reel base 301 then rotates counterclockwise thereby allowing the tape 316 to be wound onto a supply reel inside the tape cassette 310.
The magnetic recording/reproduction apparatus 300 having the above configuration is provided with sensors which detect whether the S reel base 301, the T reel base 302, and the rotary head cylinder 318 are rotating normally. If an abnormality is detected by any of the sensors, the operation is normally stopped to perform a relief operation.
FIG. 38 schematically illustrates a state of tape slacking generated when the apparatus is in the state shown in FIG. 40. Referring to FIG. 38, the state of the abnormality and a normal conventional relief operation will be described.
First, in the case where an abnormality occurs in the T reel base 302 on the tape winding side during reproduction, thus failing to wind the magnetic tape 316 onto the reel on this side, the system detects abnormal rotation of the T reel base 302 and stops the reproduction operation. However, the capstan 320 continues sending the magnetic tape 316 despite the occurrence of the abnormality until the capstan's operation is stopped, causing slacking of a portion of the magnetic tape 316 (portion 316V) between the capstan 320 and the T reel base 302. In such a case, since the system has detected the abnormality at the T reel base 302, the magnetic tape 316 is wound onto the reel on the S reel base 301 before the cassette 310 is ejected.
Secondly, in reverse, in the case where an abnormality occurs in the S reel base 301 on the tape winding side during reverse reproduction, thus failing to wind the magnetic tape 316 onto the reel on this side, the system detects abnormal rotation of the S reel base 301 and stops the reverse reproduction operation. However, the capstan 320 continues sending the magnetic tape 316 despite the occurrence of the abnormality until the capstan's operation is stopped, causing slacking of a portion of the magnetic tape 316 (portion 316U) between the capstan 320 and the S reel base 301. In such a case, since the system has detected the abnormality at the S reel base 301, the magnetic tape 316 is wound onto the reel on the T reel base 302 before the cassette 310 is ejected.
More specifically, in the case where the system detects an abnormality during tape running as described above, the following sequence of operations are normally performed. The system stops the rotation of the capstan 320 and at the same time warns a user to remove the cassette 310. Upon the pressing of an eject button by the user, the tape is unloaded while the slacked portion of the tape is being wound onto the reel on the reel base opposite to the abnormal reel base, and then the tape cassette is ejected.
With the configuration and operation described above, however, the tape cassette may sometimes fail to be ejected safely if the apparatus is under the following conditions.
First, consider the case described above where abnormal rotation occurs in the reel base on the tape winding side during tape running, causing slacking of the magnetic tape, and the magnetic tape is unloaded by being wound onto the reel on the reel base opposite to the abnormal reel base. During the unloading, guide pins 317B move in the directions indicated by respective arrows shown in FIG. 38, returning to the positions shown in FIG. 41. Following the movement of the guide pins 317B, the slacked portion 316V or 316U of the magnetic tape 316 shown in FIG. 38 is wound in the tape cassette. This means that the slacked magnetic tape (316V or 316U) is wound in the tape cassette in an unstable state without being guided by the guide pins 317B. Therefore, during the winding, the magnetic tape 316 may possibly be caught by a nearby member and damaged, or oil or grease applied to a nearby member may be deposited onto the magnetic tape 316. This fails to ensure a safe winding operation.
Secondly, in the case where an abnormality occurs in the S reel base 301 on the tape supply side during reproduction thus failing to supply the magnetic tape 316, not only the S reel base 301 but also the T reel bass 302 stop rotating. Since the S and T reel bases 301 and 302 stop rotating simultaneously; the system may fail to detect in which reel base the abnormality has occurred, or may even mistakenly detect an abnormality. More specifically, the system may possibly determine that the T reel base 302 is abnormal and attempt to wind the magnetic tape 316 onto the reel on the S reel base 301 during the unloading and eject the tape cassette 310. In such a case, since the S reel base 301 is actually abnormal and unable to wind the magnetic tape 316, the tape cassette 310 may be ejected while the magnetic tape 316 is left slacked during the unloading, causing tape damage.
Likewise, in the case where an abnormality occurs in the T reel base 302 on the tape supply side during reverse reproduction failing to supply the magnetic tape 316, not only the T reel base 302 but also the S reel base 301 stop rotating. Since the S and T reel bases 301 and 302 stop rotating simultaneously, the system may fail to detect in which reel base the abnormality has occurred, or may even mistakenly detect an abnormality. More specifically, the system may possibly determine that the S reel base 301 is abnormal and attempt to wind the magnetic tape 316 onto the reel on the T reel base 302 during the unloading and eject the tape cassette 310. In such a case, since the T reel base 302 is actually abnormal and unable to wind the magnetic tape 316, the tape cassette 310 may be ejected while the magnetic tape 316 is left slacked during the unloading, causing tape damage.
Moreover, in the case where the system detects that dew condensation is generated inside the apparatus and the magnetic tape 316 sticks to the rotary head cylinder 318, the magnetic tape 316 is unloaded while being wound onto the reel on either the S reel base 301 or the T reel base 302, and the tape cassette 310 ejected. During this operation, the magnetic tape 316 may not be sufficiently wound onto the reel, causing tape damage. Hereinbelow, the case where the magnetic tape 316 is wound by the T reel base 302 will be described as an example.
Referring to FIG. 40, when dew condensation is generated during recording/reproduction and the magnetic tape 316 sticks to the rotary head cylinder 318, the system detects this occurrence, and stops the rotation of the capstan 320 to stop the recording/reproduction operation. The system then moves the pinch roller 319 away from the capstan 320, putting the apparatus into an eject standby state. When the magnetic tape 316 is unloaded, the guide pins 317A and 317B move to respective positions shown in FIG. 41, and the S reel base 301 or the T reel bass 302 operates to wind the magnetic tape 316, to reach the state shown in FIG. 39. As shown in FIG. 39, however, although the portion of the magnetic tape 316 located right with respect to the rotary head cylinder 318 (portion 316T) has been wound on the reel on the T reel base 302, the portion of the magnetic tape 316 located left with respect to the rotary head cylinder 318 (portion 316S) may sometimes be left slacked not being wound on the reel on the T reel base 302 since the magnetic tape 316 sticks to a portion 318A of the rotary head cylinder 318. Tape damage occurs if the tape cassette 310 is ejected in this state. This phenomenon also occurs when the magnetic tape 316 is wound by the S reel base 301, in which the magnetic tape 316 is left slacked on the right side with respect to the rotary head cylinder 318.
As described above, in the conventional abnormality relief operation, tape damage may occur during the cassette ejection, failing to ensure safe cassette ejection.
The object of the present invention is to provide a magnetic recording/reproduction apparatus having a mechanism in which, when the rotation of the T reel base or the S reel base abnormally stops during a normal tape recording/reproduction operation or when dew condensation is generated inside the apparatus, the S reel base and the T reel base are rotated in sequence by a predetermined amount in the direction of winding the tape after the pinch roller is moved away from the capstan, so that slacking of the tape generated due to the abnormality is eliminated allowing the tape to pass along guide pins to establish a nearly ideal tape path and thus ensuring smooth operation without occurrence of tape damage during a subsequent operation.